Findings suggest humankind invented earthenware pottery 20,000 years ago, while still living as hunter-gatherers during the height of the last ice age.

A team of researchers working in China, including an Israeli professor, have found evidence that humans used earthenware pottery some 20,000 years ago – 2,000 years earlier than previously thought.

The findings were discovered and dated by a team of researchers led by Prof. Wu Xiaohong in the Jiangxi Province in eastern China. The team included Israeli archaeologist Prof. Ofer Bar-Yosef, who recently returned to Israel after 24 years at Harvard University.

Earthenware pottery was one of primitive human's most important inventions, changing the way humans produced and consumed food.

For dozens of years, researchers believed that humans first developed earthenware pottery during the agricultural revolution of the Neolithic Period, some 10,000 years ago, when humans first began to domesticate plants and animals and moved from a nomadic existence to a sedentary lifestyle.

Since the 1990s, however, various archeological discoveries, mostly in China, have led researchers to believe that clay pottery pre-dated the agricultural revolution.

According to the new findings, which will be published on Friday in the journal Science, humans first began using clay vessels some 11,000 years before the agricultural revolution in China, during a period in which people still lived as in small nomadic groups of hunter-gatherers.

Speaking to Haaretz, Prof. Bar-Yosef said the new findings change the way archaeologists view the hunter-gatherers of the Paleolithic Period. "The paradigm that assigned clay pottery to the agricultural revolution is crumbling," he said.

What was pottery used for 20,000 years ago? Bar-Yosef called this "one of the most difficult questions." It is known that in later periods earthenware was used for cooking, collecting food, drinking and rituals.

"The assumption is that pottery was used for cooking, because there are signs of external burns. What did they cook inside? We are not one hundred percent sure. Sometimes they extracted sap from animal bones that way," he said.

According to the new findings, humans developed clay pottery during the peak of the last Ice age, raising questions about how and why such a momentus invention occurred during one of the most difficult climatic periods humankind has ever endured.

"The height of the last Ice age was the coldest period ever on Earth," said archaeologist Prof. Gideon Shelach of The Hebrew University of Jerusalem, calling prevailing climatic conditions during the period "the worst conditions imaginable." Shelach's article, which puts the discoveries in a wider historical context, will also be published in the new issue of Science.

According to Shelach, the new findings reinforce the view of some scientists that the transition to domesticated agriculture was set into motion by external factors linked to environmental changes.

"Today there is a more-or-less accepted explanation which asserts that at the height of the Ice age there were fewer resources, and thus people developed methods that allowed them to take maximum advantage of [them]."

According to one theory, earthenware vessels were used to cook the bones of hunted animals, in order to get the most nutritional benefit from them.

Shelach offers another hypothesis. "People were pushed into living in crowded conditions, and then feasts and celebrations developed, which may have included the making of alcohol, in order to reduce the social pressures that were created. Pottery may have been used to brew and store the alcohol," he said.

Could the invention of clay pottery actually have taken place even earlier? According to Bar-Yosef, anything is possible. "Perhaps they began making clay pottery a thousand years earlier. As an archaeologist with decades of experience working in the field in multiple countries, my principal is that if you don't dig, you won't find."